Mid-Pliocene microfossils

Microfossils used in mid-Pliocene paleoclimate research. Clockwise from top left: ostracode, planktic foraminifer, diatom, benthic foraminifer, and pollen grain. One way scientists reconstruct past climate is by comparing the spatial distribution of these microfossils with the distribution of their relatives living in today's climate. Calcareous microfossils (foraminifera and ostracoda) carry additional climate information in their elemental ratios; for example, the ratio of magnesium to calcium varies with ocean-water temperature, and the ratios of different isotopes of oxygen vary with global ice volume and, therefore, sea level.